Between flights, commercial and military aircraft typically park at a terminal facility. When parked, the aircraft engines are generally powered down for ground crew safety. Electrical power that would otherwise be supplied by the aircraft engines may be supplied by an external source, such as a ground power cart or a generator associated with a sky-bridge, an aircraft carrier for NAVY applications or an aircraft hanger. A ground power connector at the end of a power supply cable couples the external power source to the aircraft. Commercial and military aircraft typically have a fixed connector somewhere on the side or underside, usually near the front or aft of the aircraft. Aircraft fixed connectors comprise a receptacle with male contact pins positioned therein. Ground power connectors comprise a plug with female sockets positioned therein, wherein the plug mates with the receptacle and more specifically the female sockets mate with the male contact pins.
The coupling between the ground power connector and the fixed aircraft connector is typically maintained by a physical engagement of the mating forces at both the plug/receptacle and pin/socket interfaces. Some configurations include straps or other mechanisms to hold the ground power connectors to the aircraft. The Engineering Society for Advancing Mobility Land Sea Air and Space (SAE) has promulgated an Aerospace Standard related to cable assemblies and attachable plugs for external electric power (SAE AS7974). If the total mating forces are not sufficient to maintain the coupling between the aircraft fixed connector (receptacle) and the ground power connector (plug), gravitational forces will disconnect the ground power connector (plug) from the aircraft fixed connector (receptacle), and the ground power connector (plug) will drop to the ground. This low force condition also contributes to high resistance between the pins and sockets which results in excess heat generation that can damage the aircraft and ground power connectors. In addition to the potential for damage to the ground power connector (plug), it is undesirable for the ground power connector (plug) to prematurely disconnect from the aircraft fixed connector (receptacle), because a disconnect results in arcing between the pin and socket contacts that can cause permanent damage to the contacts and a loss of power supply to the aircraft.
A socket contact is a female contact designed to mate to a male or pin contact. It is normally connected to the “line” side of a circuit. It is also important for each of the individual female sockets of the ground power connector (plug) to maintain physical engagement through coupling forces with each of the corresponding individual male pins of the aircraft fixed connector (receptacle). When physical engagement through coupling forces is not maintained between a pin and a socket, electrical arcing may generate excessive heat and increased electrical resistance to the power supply. Electrical arcing and excessive heat may prematurely damage the pin or the socket.
In typical commercial and military terminal operations, ground power connectors are coupled/decoupled to/from several different aircraft each day. The simple action of inserting the ground power connector (plug) into an aircraft fixed connector (receptacle) wears mating surfaces at both the plug/receptacle and pin/socket interfaces. Such wear may contribute to insufficient mating forces to maintain physical engagement. Further, such wear at the pin/socket interface may lead to poor physical engagement so as to result in electrical arcing and excessive heat at one or more of the individual pin/socket interfaces.
Other typical wear occurs when ground power connectors are removed from the aircraft and fall to the ground causing abrasion to the surfaces of the connectors. Typically this abrasion occurs on the front corners of the connectors. When severe, the corners are worn past the rubber and expose the ground operations personnel to exposed socket surfaces. To a lesser degree, abrasion occurs on all of the surfaces when the connectors a dragged across the ground surface during storing and deploying operations.
One industry solution to address these problems is to use a ground power connector (plug) that has a disposable connector saver or a replaceable nose at the end for engagement with aircraft. When the useful life of the disposable connector saver or replaceable nose has come to an end, it is only required to replace the disposable connector saver or replaceable nose, rather than the entire ground power connector (plug).
Standard connector savers or replaceable noses are attached through a non-standard set of mating contacts, which renders the back section of the connector useless for connecting to aircraft. Typical ground power connectors (plugs) that use a connector saver or replaceable nose have no interface to engage an aircraft unless a connector saver or replaceable nose is attached to a base portion of the ground power connector (plug). Thus, once a connector saver or replaceable nose has become inoperable, the entire ground power connector (plug) is inoperable until a new connector saver or replaceable nose is attached to the base portion of the ground power connector (plug).